Imaging technologies including x-ray computed tomography, magnetic resonance imaging (MRI), positron emission tomography (PET), and many others have found widespread use in applications as diverse as medical imaging and cargo inspection. Imaging techniques involve measuring a property of an object across an array of voxels in three-dimensions. For example, x-ray imaging techniques involve aiming a beam of x-ray radiation at the object to be imaged and measuring the intensity of x-rays received through the object. The attenuation of the x-ray beam depends on material properties of the object such as mass density or effective atomic number. Using imaging techniques, it is possible to reconstruct a three-dimensional or projected two-dimensional image of the object.
In security applications, the three-dimensional volumetric or two-dimensional projection images can be used to detect suspicious or dangerous objects hidden in baggage or cargo, for example, contraband. In medical applications, the three-dimensional volumetric or two-dimensional projection images can be used to detect organic or inorganic structures related to disease or injury within a biological organism.